This reverts commit dce75ab4cf647eec6699f8a30ba2289a3738b307.
This also makes some small changes to make onBenchmark a
JSExportedDartFunction instead of a JSBoxedDartObject. This is for
changes in https://github.com/flutter/flutter/pull/129436 and to account
for the fact that flutter/packages provides an `allowInterop`'d
function. Benchmarks tests pass with this CL.
## Pre-launch Checklist
- [X] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
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responsibilities.
- [X] I read and followed the [Flutter Style Guide] and the [C++,
Objective-C, Java style guides].
- [X] I listed at least one issue that this PR fixes in the description
above.
- [ ] I added new tests to check the change I am making or feature I am
adding, or Hixie said the PR is test-exempt. See [testing the engine]
for instructions on writing and running engine tests.
- [X] I updated/added relevant documentation (doc comments with `///`).
- [X] I signed the [CLA].
- [ ] All existing and new tests are passing.
49e8ec8b0b